refactor the way of getting controls owned by the form

[tigercosmos]

servo/components/script/dom/htmlformelement.rs

Lines 495 to 498 in a1abdde

	fn static_validation(&self) -> Result<(), Vec<FormSubmittableElement>> {
	let node = self.upcast::<Node>();
	// FIXME(#3553): This is an incorrect way of getting controls owned by the
	// form, refactor this when html5ever's form owner PR lands

#3553 is closed.
There is a merged PR in #15938.

[tigercosmos]

cc @KiChjang

[jdm]

I don't think that code has been updated to take advantage of the changes in #3553 yet.

[tigercosmos]

I think we usually fill the issue number, which is opened for the description, into FIXME(#<number>).

In this case, maybe modifying this comment to avoid misleading is better.
And since the PR is already merged, it could be:

// FIXME: This is an incorrect way of getting controls owned by the 
//        form, should refactor this based on html5ever's form owner(#3553)

[KiChjang]

I think the better solution here is to fix the underlying issue, rather than to fix the wording of the comments. @tigercosmos Do you want to make a PR for the changes?

[tigercosmos]

I can have a try. I don't look much about this code. @KiChjang Do you remember why you said it is incorrect, and what do you expect it would be like?

[pshaughn]

At least one thing is testably wrong relating to this. html/semantics/forms/the-form-element/form-nameditem.html expects an earlier <input form=a name=b> to be picked up when a <form id=a></form> appearing later in the page is going through its controls, and it doesn't find it. (broke this out into its own issue #25711)

[pshaughn]

There's a FIXME(#3553) that probably really means this issue.